Modeling-based examination of conducted EMI emissions from hard and soft-switching PWM inverters

For the purpose of investigation of electromagnetic interference (EMI) mechanisms in hard- and soft-switching PWM inverters, empirical models and comparative experiments were studied in both time-domain and frequency-domain. Models of the major circuit components including switching devices, passive components and interconnects were obtained with physics-based device modeling and time-domain reflectometry (TDR) for parasitics characterization. The inverter simulation was then constructed using all the empirical models, and the results were compared with those from prototype experiments to examine the significant roles of parasitic elements coupled with device switching dynamics in EMI generations. With separation of common- and differential-mode EMI, the modeling approach is demonstrated to be effective over most of the EMI frequency range and the soft-switching effects on EMI are discussed